This application claims priority to U.S. patent application Ser. No. 13/875,026, filed on May 1, 2013, entitled “System and Method for Delivering Content in a Unicast/Multicast Manner,” which claims priority to U.S. patent application Ser. No. 12/638,216 filed on Dec. 15, 2009, entitled “System and Method for Delivering Content in a Unicast/Multicast Manner,” now U.S. Pat. No. 8,467,419, which claims priority to U.S. patent application Ser. No. 11/240,098, filed on Sep. 30, 2005, entitled “System and Method for Delivering Content in a Unicast/Multicast Manner,” now U.S. Pat. No. 7,656,908, which claims priority to U.S. patent application Ser. No. 10/026,227, filed Dec. 21, 2001, entitled “System and Method for Delivering Content in a Unicast/Multicast Manner,” now U.S. Pat. No. 7,082,142. The entire disclosure of these prior applications is considered as being part of the disclosure of the accompanying applications and hereby expressly incorporated by reference herein.
The present invention relates to content delivery, and more particularly to a system and method for enabling multicast synchronization of unicast information streams
In conventional packet, frame or cell based systems there are typically two modes of communication: point-to-point (also known as Unicast) and point-to-multipoint (also known as Multicast). Generally, Unicast is communication between a single sender and a single receiver over a network as opposed to multi cast which is a communication between a single sender and multiple receivers.
Multicast is a receiver-based concept: receivers join a particular multicast session group and traffic is delivered to all members of that group by the network infrastructure. The sender or content provider does not need to maintain a list of specific receivers since only one copy of a multicast message will pass over any link in the network, and copies of the message will be made only where paths diverge at a router. Thus multicasting yields many performance improvements and conserves bandwidth end-to-end in the network.
Some examples of multicasting applications include the transmission of corporate messages to employees, communication of stock quotes to brokers, video and audio conferencing for remote meetings and telecommuting, and replicating databases and web site information. Multicasting efficiently supports these types of transmissions by enabling sources to send a single copy of a message to multiple recipients who explicitly want to receive the information. This is far more efficient than requiring the source to send an individual copy of a message to each requester such as is done in a unicasting manner, in which case the number of receivers is limited by the bandwidth available to the sender. It is also more efficient than broadcasting one copy of the message to all nodes (broadcast) on the network, since many nodes may not want the message, and because broadcasts are limited to a single subnet.
In spite of the various benefits affording by multicasting, unicasting has the unequalled benefit and flexibility of allowing users to select different types of content at their leisure and on their specific timeframes as opposed to being bound by the constraints of a multicast presentation. For example, typically, once a multicasting sessions begins, those who request to join the multicast sessions thereafter will only receive the multicasted content from the point on at which they joined as to opposed to having the content start from the beginning as in conventional unicasting.
Accordingly, it would be desirable to have a system and method which combines and integrates the various benefits and savings attributed to both unicasting and multicasting.